Gardening Articles: Landscaping :: Container Gardening & Ponds

On Goldfish Pond (page 2 of 3)

by Steven A. Frowine

Keeping Goldfish Healthy

Most goldfish are naturally hardy and require only a few conditions to keep them in good health. One of the most common problems arises from adding too many fish to a pool. The result is that fish waste pollutes the water, which becomes the perfect habitat for green algae to form. Green algae grow suspended in the water, turning it murky green and making it difficult to see the fish. Excessive algae can kill fish. If the algae suddenly die or are killed with chemicals, the decaying plants will use more oxygen, and as a consequence, the fish will suffocate.

At a maximum, add only one fish for every 30 gallons of water; fewer are even better. If your pool or pond has no filtration or aeration, reduce the number still further. Also the larger the surface area of the pool or pond, the more oxygen there will be in the water.

The best time to add goldfish to a pool or pond is in early spring after the water temperature has reached 60oF. The water should contain no chlorine or ammonia. Many municipal water companies add chloramine (a combination of these chemicals), which is very toxic to fish. To be safe, you can add a water conditioner such as Amquel, available from aquarium stores, that neutralizes both of these chemicals.

Plants are critical elements in a water garden and are appreciated as much by the fish as by the gardener. They provide protective cover for the fish and absorb nutrients in the water, substantially reducing green algae blooms. Goldfish are compatible with most plants. I've planted cannas, water lettuce, nymphaeas, sedges, and waterlilies in my water gardens. As long as the fish populations aren't too high, you should not experience noticeable plant damage.

Overfeeding is the most common cause of death or decline among goldfish. If your pool is well planted, it is not necessary to feed the fish at all except, perhaps, when you first add them; they will have plenty to eat with the existing populations of algae, mosquito larvae, and other water insects. However, feeding the fish brings them to the surface so you can better enjoy their bright colors.

If you choose to feed your goldfish, use a commercial pellet food such as Hikari or Nippon, giving them only as much as they can consume within 5 minutes. If you give them too much, the extra food pollutes the water and ultimately kills the fish. Replacing 10 percent or so of the water in your pool with neutralized tap water every few weeks is a simple yet effective way to protect against any accumulation of pollutants from fish waste or overfeeding. Goldfish eat very little when the water is cold, as in spring and fall, so take care not to feed them when temperatures in your area dip to 50oF.

Goldfish can be kept outdoors for most of the year. I keep mine in two 4- by 8-foot, 3-foot-deep aboveground pools, which I constructed. These pools, lined with PVC, which lasts for 10 to 20 years, are easy to maintain. Because the pools are raised, you can sit on the edge to observe the fish up close. Keeping your fish in a small pond is another option, though a less appealing one when it comes to protecting them from predators.

The most common goldfish predators are herons, raccoons, and cats. All of these animals will wade into water to stalk the fish. The most effective means of guarding against these predators is to use an aboveground pool with straight, deep sides so they can't wade in. The fish will be able to quickly swim to the bottom to escape any predator able to perch on the edge. Another option is to cover the pool or pond with netting at night.